Have you ever been on a hike and seen a small mammal eating a mushroom? Have you ever wondered if there is some ecological interaction going on between the animal and the fungus? Well I have, and a new publication by Mellissa Danks et. al. 2020 focus on a cute Australian marsupial known to have quite the appetite for mushrooms. The swamp wallaby is just one of many mammals that consume fruiting bodies. There are multiple studies that reveal mycophagous animals disperse spores, but many focus on truffles and truffle like fungi. These subterraneous fungi entice mammals to eat them and disperse them to other areas of the forest. This new study reveals that true mushrooms, the aboveground fruiting bodies we know and love can have their spores dispersed by wind and an animal counterpart. Why else would there be so many species of mushrooms edible to mammals?    

These researchers first uncovered how long it takes for spores to pass through these animal’s digestive system. Then, they tracked 12 swamp wallabies varying in size, sex and age using GPS telemetry. With these animal’s movements recorded, these researchers concluded that swamp wallabies disperse fungal spores hundreds of meters away from the sites they consumed their mushroom snack. On some occasions, wallabies dispersed spores nearly 1,300 meters away! These distances are significant when it comes to mycorrhizal fungi.

You don’t need me to tell you how important mycorrhizal fungi is. Especially in Australia though, with some of the most ancient, nutrient poor soils on the planet, we can see the importance of mycorrhizae and its dispersal. The eastern part of Australia is filled with mycorrhizal trees, one of which, and living fossil just recently discovered called the Wollemi pine. The Wollemi pine associates with arbuscular mycorrhizae, a type of mutualistic fungi that doesn’t produce big mushrooms like its ectomycorrhizal counterpart. It is important to realize that any mycorrhizal dispersal can enhance forest connectivity and increase the overall health of the system via soil and water retention. 

We tend to focus on the evolution of fungal toxins that deter mycophagy, but you have gone to the supermarket and seen several edible species. Many mushrooms are edible and edible for a reason. The poisonous ones are poisonous to us, but many times, are readily eaten by other species that may have been selected for to spread their spores. Just last summer I found a deadly poisonous Amanita bisporigera that had been largely munched away by slugs. Guaranteed those slugs survived.

The Class Mammalia took over in the wake of the K-T extinction. Since then, 65 million years have passed, which a sufficient amount of time for the evolution of fungal traits to maximize their own fitness by using mammalian dispersers. Here is an example of fungal dispersal from an Australian marsupial. They disperse ectomycorrhizal fungi which still positively impacts arbuscular mycorrhizal trees, like the endangered Wollemi pine. We now have concrete evidence that generalist marsupials from down under, disperse ectomycorrhizal spores and enhance forest connectivity. Ecology is incredibly fascinating to me seeing as one feeding strategy of just one species has enormous implications of hundreds of other forest species. 

[Link 1]